Control mechanism for burners



Feb 29, 1944- R. w. .JOHNSON ET A1.

CONTROL MECHANSM FOR BURNERS Filed July 19, 1941 3 Sheets-Sheet lINVENTO OH W fO//A/ ma uxq ATTORNEY.

Feb. 29, 1944. O R-W JOHNSON ETAL 2,343,188

CONTROL MECHANISM FOR BURNERS Filed July 19, 1941 3 Sheets-Sheet 2INVENTORs Fav nl. JMA/50M TTORNBY Feb. 29, 1944. R W JOHNSON ET AL2,343,188

CONTROL MECHANISM FOR BURNERS Filed July 19, 1941 3 Sheets-Sheet 3 a I 7O 6. 40 #$7 v'mn-nun a 35 52K olli! III ATTORNEY.

Patented Feb. 29, 1944 CONTROL MECHANISM FOR'BURNERS Roy W. Johnson andWilliam A. Biermann, Milwaukee, Wis., assgnors to Automatic ProductsCompany, Milwaukee, Wis., a, corporation oi' Wisconsin Application July19, 1941,' Serial No. 403,120

17 Claims.

This invention relates to an improvement in a control mechanismespecially designed and adapted for use with heaters of the type whereinthe heater is red by a liquidv fuel oil burner.

A typical installation is one in which a hot air furnace or heateremploys a pot type burner, or its equivalent, to which oil or liquidfuel is fed by gravity under the control of a metering valve embodied ina constant level oil control device, and in which air to supportcombustion yis supplied to the combustion chamber of the burner byVmeans of an electric motor-driven fan.

One of the objects of the present invention is to provide a controlmechanism of this character which automatically regulates the action ofthe metering valve and the electric motor-driven fan f in such fashionthat the fan is not turned on until the metering valve hasbeen opensuinciently to raise the fiame to an extentnecessary to require theforced draft to sustainpropercombustion,land, also, to anextent whichprecludes the possibility ofthe forced draft extinguishing f the flame.

Another object of the invention is to provide a control 'mechanism'ofthis character 'and having the advantages mentioned, which also providesfor continued operation of the fan after the metering valve has beenshifted to low or pilot re position, thereby `preventing the formationof carbon or soot and insuring clean, complete, and odorless combustionat all times.

A further object of the invention is to provide a control mechanism ofthis character, which is simple, compact, and closely organized inconstruction, easy and comparatively inexpensive to reliable and ment..and combination of parts, which will bev hereinafter more fullydescribed and particularly pointed out in the appended claims, referencebeing had to the accompanying drawings forming a part of thisspecification, and in which:

Figure 1 is a view in top plan of a control justable control knobremoved and witli the cover for the control housing shown in transversesection, all for the sake of illustration;

Figure 4- is a view in'bottomplan of the terminal board of the controlmechanism and of the parts carried thereby; I 4

Figure 5 is a view partly in side elevation and partly in vertical,longitudinal section, taken on line 5 5 of Figure 1, parts being omittedfor the sake of simplicity in illustration;

Figure 6 is a fragmentary section view taken4 on line 6-6 of Figure 1,parts being omitted for the sake of simplicity in illustration;

Figure ,7 is a view in transverse, vertical cross section, taken -online 1-1 of Figure 5, with parts shown in elevation for the sake ofsimplicity in illustration;

Figure 8 is afragmentary, sectional view similar to Figure 5 andillustrating the snap-acting switch in its closed position;

Figure 9 is a group view in perspective of parts of the snap-actingswitch;

Figure 10 is a fragmentary view in vertical cross section illustratingthe metering valve construction and the manually operable cam means foradjusting the same;

f Figure 1l isa diagram of the electric circuits` embodied in thecontrol mechanism;`

Figure l2`is a view similar to Figure 3 show` ing a modified form of theinvention; and

Figure 13 is a fragmentary view intop plan illustrating the keeper slotfor the heat motor latching lever. c

`Referring to the drawings it will beseen that the constant level oilcontrol device in which the present invention is embodied comprises amain casing, designated generally at Il, and having a liquidsuppiychamber I2 therein.A Liquid fuel `is supplied to and maintained at aconstant level in said chamber I2 by mechanism (not shown) but wellknown and widely used in this art and fully disclosed and claimed inUnited States Letters Patents 2,068,138, granted January 19, 1937, and2,120,364, granted June 14, 1938.

The liquid flows out of the main chamber I1 mechanism'embodying thepresent inventionap-s through an outlet passage I) which is connected tothe burner (not shown). A tubular valve guide I4 has its lower endpress-fitted or otherwise suitably secured in the upper portion in the.outlet passage I3, the valve guide I4 extending vertically in thecasing II and terminating a short distance below the cover I5 of themain casing II.` The valve guide is provided with'lat-` eral port oropening I6A which establishes communication between the interior of thevalve guide I4 and the liquid supply chamber I2.

A metering valve I1 is slidably fitted inthe tubular guide I4 and metersor regulates the ow from the supply chamber-I2 to the burner.'- A springI8 biases the metering valve I1 to open position.

A manually adjustable control knob I9 is mounted on the cover I5 of'-the main casing above the metering valve I'I and acts through a cam 20with which it is interconnected to control `the position of the meteringvalve I1. The

I lactive-face of the cam 20 rides on an abutment lug 20a which may beintegrally formed with an adjustable abutment supporting arm 20h. Anadjusting screw 20c controls the position of the supporting arm 20h andconsequently the position of the abutment lug 20a. When the knob I9 isturned, the cam 20a, riding on the abut-- ment lug 20a,fwill raise orlower the knob I9, dependingupon the direction of rotation ofthelknob,'and Willfalso correspondingly raise yand lower a valve-operatingstud 20d xed to and movable with the knob I9, and having its lowerendfbearing on the upper end of the metering v4I and being secured invalve I1 so as to control the position thereof.

The knob I9 may be adjusted to cause the cam 20 to ymove the meteringvalve to completely closed or shutting oil position, orv it may beadjusted to allow the valve I1, under the regulation of its thermostaticcontrol means to be hereinafter more fully described, to vmove to fullopen position, o r to any one of several intermediate positions, asindicated by the `scale or dial designated at D in Figure 1. y

In Aaddition to the manually operable cam means, lever mechanism,designated' generally at 22, is provided, the lever mechanism 22 havling a lever, arm 23 engageablewith the laterally extending guide pin 24of the metering valve I1, and` also having a lever arm 25 engageablewith the lower headed end of a pin 26 slidably-fltted .in a bearing 21provided therefor on the cover I5 of the main casing Il. High and lowfire stops, designated at 28 and 29, control the extreme position of thelever mechanism 22.

Details of the construction of the metering valve I1 and its levermechanism 22 need not be further described since per se they are notpart of the present invention and are fully disclosed and claimed in theapplication of Roy'W. Johnson, one of the joint inventors of this case,for "Conversion oil controldevices, filed April 4, 1940, Serial No.327,789.

vA control unit, designated generally at C', is supported on 'anddetachably ysecured to the cover I5 .of the main casing II. The controlunit C includes a sheet metalcasing or housing, designated generally at30, which may comprise a bottom plate, parallel, vertical sidewalls 32,upturned cross flange 33 extending transversely of-the rear edge oi thebottom plate 3|, and

transversely extending and spaced upright front pieces 34-integral withthefront edge of the hottom plate 3l. A removable top or cover 35ccmpletes the enclosure afforded bythe housing 30. The cover 35 isremovable, but when assembled and 'is threadedly engaged with,.internaily4 threaded openings providedA 'i'n attaching lugs 31 fixedto the side Walls 32 of the housing 30.

.Screws 3B detachably secure the controlunit to thecover lplate I5 ofthe main casing II.

A horizontally disposed terminal board or panel 40 of insulatingmaterial is supported within the control housing 30 above the bottomplate-3l thereof by means of posts 4|, the terminal board 40 resting onthe tops of the posts position thereon by screws 42,

'A heat motor of the relay, auxiliary heater type, designated generallyat H, is supported on the under side ofthe terminal board 40. 'I'he heatmotor H includes a bimetallic or thermostatic strip or leaf 45, whichhas combined therewith an electric heating ,element or resistance 46engaged in a wrapping 41 of mica or other 1suitable electric insulatingmaterial.V Rivets or the like 48 coact with the mica casing or wrapping41 of theheating element 46 vand with the bimetallic leaf 45 to securethe heating element in position on thevbimetallic leaf `in heat inter-lchanging'relationship therewith. Oneend of the leaf 45 is fixed toabracket 49 suitably secured to the under side ofthe 1panel k40. Avalve-operating arm 50-is riveted as at 5I to the free end of thebimetallic leaf 45. vThis arm 50 projects through an opening providedtherefor in the front of the control housing and has its outer endupwardly offset, as at 52, and overlying themotion transmission pin 26.The portion 52 of the .arm which overlies the -pin 26 is provided witharm is equipped with a washer or collar 51 to retain it assembled withthe arm. l A coil spring 60 encircles the stud below `the arm 52 and hasone arm bearing against the head56 of the stud 55 and itsopposite armbearing against the under side ofthe upwardly oiset end 52A of thevalveoperating arm 50. 'Thestud 55 and its spring 60 provide a yieldableor lost motion connection between the valve-operating arm A50 and themotion transmission pin 26, for a purpose which will hereinafter moreclearly. appear. Av sheet metal guard 6I secured to` thefront-pieces 34of the control housing 30 surrounds andprotects the valve-operating/arm50, its valve-operating stud 54, and the pin 26.

A snap-acting toggle switch, designated generally at S, is connected jincontrolling relation totheelectric motor E, which drives the fan orblowerF. f

The snap-acting switchS includesa fixed contact, designated generallyYat 6 5, the fixed contact 65 having a contact buttont supported by acontact carrier strip B1 which is secured to and supported on as well asin with the terminal or binding post 2 carried by the panel 40. Amovablecontact button` 68 is cooperably related to the fixed contactbutton 66. e The movable contact button 68 of the switch S is controlledbyra toggle mechanism of .special construction; As illustrated inFigures 4, 5, 8, and 9, this toggle mechanism comprises stiillyresilient toggle members T and portions of a one-piece sheet metalstamping M. The stamping M is stamped or punched out of good electricalcontact T' constituted by "2,343,188 -a thin 4sheet'of spring steel orother appropriately resilient metal of good electrical conductivity, andis fashioned with side members 18 and 18' cross connected at its ends byintegral endmemy bers1| and 12. The end member 1| is tapered member 12has a centrally disposed, inwardlyr directed finger 12' integrallyformed therewith, the inner end of the finger 12' being tapered andbeing longitudinally alined with, though slightly spaced-from, thetapered projection 1|. Intermediate portions of the side members 18 and18 are xedly supported on, though in spaced relation to, the under sideof the terminal board 48, and this may be conveniently accomplished bymeans of rivets 13, spacing sleeves 14, and washers 16, which alsoserve'to secure a stopbracket 16 in position. The rivets 13 have theirupper ends headed, and in the assembly these rivets have their shanksextended through openings provided therefor in the terminal .board 48,through alined openings 16 in the body portion of the stop bracket 16,through the spacing sleeves 14, past intermediate portion of the inner kedges of the side members 18 and 18Tj of the sheet metal stamping M andthen through 'the washers 15. The lower ends of the rivets'are staked orriveted over into tight" andv secure'engagement with -the washers 15 soas to clamp intermediate portions of the side members 18 and 18 of thesheet metal stamping M between the lower ends of the spacing sleeves 14and the washers 15,

and incidentally also clamp the stop bracket 16` against the under sideof the terminal board 48. The rivets 13, spacing sleeves 14, washers 15,and stop bracket 16 are constituted of metal of good electricalconductivity, and together with the sheet metalstamping M serve toelectrically connect the `.movable contact button 68 with the terminalor binding post the shank of which post I passes through an opening inthe terminal board 48 and has its lower end mechanically secured to andin good electrical contact with the stop bracket l16. The toggle switchS is completed by a toggle spring 11 compressed between spring cups 18and 19, the bottoms of which are indented orsocketed to adapt them tobev interfltted with the tapered projection 1| of toggle arm or member Tand the tapered ends of finger 12' of toggle arm T', respectively. It'will be understood from the foregoing description that the toggle armor member T is constituted of the end member 1|, its finger 12', and theportions of the side members 18 and 18' located on the left hand side ofthe spacing sleeves 14 and washer 15 as viewed in Figures 4 and 5.

A switch operator 80, in the form of a strip'of insulating material, hasa portion securely fixed by rivets 8| to the finger 12' and end member12 Y of the toggle arm T' of the stamping M. The

switch operator 88 projects beyond the end member 12 and its outer orfree end is interposed between switch actuating elements, designatedgenerally at 82 and 8.3, respectively. These elements 82 and 83 areadjustably supported on an angle bracket 84 connected to andmovable'with the-valve operatingarx58, and in fact the brack et 84may'btconviently made an integral part of the valve-operating arm 58although it projects laterally therefrom and is offset upwardly withrespect thereto. The switch-actuating elements 82 and'83 are ofidentical construction and each has a knurled knob` 8 5 at its upperend, is formed with a threaded shank portion 86, which is interthreadedwith an opening provided therefor'in the bracket 84, and has an annularBange or col lar 81 engageable with the switch operator. The arrangementis such, however, that the collar 81 of the switch-actuating element 82is below the switch operator whereby the flange or collar 81 of theoperator 83 is above the same.

When the valve is moved to closed position, the valve-operating arm 58descends. This moves the bracket 84 downwardly, bringing the actuatingelement 83 into engagement with the switch operator 88,` therebyshifting the toggle arms T and T' to the position shown in Figure 5.This moves the contact 68 away from the fixed contact 66 to open-theswitch.

An abutment orstop 98 limits the extent to which the contact `6|!mayvmove away from the contact 66, this abutment or stop being ofinsulating material and being carried by a bracket 8| which is supportedon the panel 48 by the terminal 2. When the valve arm 58 moves upwardlytov allow the metering valve toopen, the switch-actuating element 82swings the switch operator 88 to `cause the toggle arms to shift to theposition shown in Figure 8, whereupon the contact `68 snaps over intoengagement with the contact 66 to close the switch.

The switch-actuating elements 82 and 83, by virtue of their threadedinterconnection with the bracket 84, are vertically adjustable, and theyare releasably maintained in any adjustment by means of split resilientlock washers 92. By providingvtwo switch-actuating elements 82 and 83,making them vertically adjustable and combining them in the mannerdescribed with the operating element 88 of the snap-actuating switch S,it is practical and convenient to so adjust these switch-actuatingelements that they will control the operation of the `burner in a,specially advantageous manner, as will be hereinafter more clearlydescribed.

As illustrated in Figure 11, a room thermostat 95 controls theenergization of the electric heating element 46 ofthe heat motor H. Oneterminal of the electric heating element 46 is connected by a flexiblewire 96 to the binding post 0r terminal 4. A wire 91 connects thebinding postor terminal 4 with the movable conductive thermostat leaf 88of room thermostat 85. A fixed contact 98 of the room thermostat isconnected by a wire |88to the binding post 5. A wiie |8| connects thebinding post 5 with one terminal of the secondary winding |82 of astepdown'transformer, designated generally at |83. The other terminal ofthe secondary winding |82 of the transformer |83 is connected to aconnector clip |84 carried by the under side of the terminal board. `Aflexible wire connects the clip |84 with the other terminal of theelectric heating element 48. The primary winding |88 of the transformer|83 has one terminal con nected by a wire |81 to the binding post A wire|88 connects the binding post l to one side of the power line. The otherterminal of the primary coil |86 of t-he transformer |83 is connected bya wire |89 to binding post or terminal 3. The binding post or terminal 3is connected by a wire ||8 to the other side of the power line. A Wireconnects the binding post |83 to one terminal ofi` the fan motor E. Theother terminal of the motor E is connected by a wire' ||2 to the bindingpost 2. As described, the binding post 2 is electrically connected tothe xed contact 65 ofthe snap-acting switch S, whereas the' movablecontact 58 of theswitch S is electrically connected with the bindingpost or terminal With this construction, when the room thermostat 95 issatised, the circuit of the electric heating element 46 of the heatmotor4H is broken,

Figure 5 so ,that the contact 69 is disengaged from f contact 66 and thefan motor` circuit is `open.

Now then, if the room thermostatV callsl for heat its leaf 98 engagesthe xed contact 99, thereby energizing the electric heating element 46of the heat motor H, causingl the bimetallic element 45 to Warpupwardly.I This so swings the valve-operating` lever 50 and partscarried thereby that pressure on the pin 26-is relieved and the valvespring I8 opens'thetmetering valve so that a higher 4flame is had in theburner. The setting of the switch-actuating element-82 is such that itdoes not come into engagement with the switch operator 80 until afterthe metering valve has opened a predetermined amount, this operationbeing desirable to avoid possible extinguishment of a low name by theforced draft;

y However, at the selected time, the switch-actu-` ating element 82engages under the outer end of the switch .operator 80 and. therebyshifts the toggle-switch from the position shown in Fieure 5 to thepositionfshown in Figure 8; In the closed position of switch S shown inFigure 8,

the contacts 68 and 65 are engaged Consequently, the circuit'through thefan motor E-is closed and the motor starts up and operates the fan tosupply air to the re pot of the burner'. When the room thermostat isfsatisfied, Athe circuit through the electric heating element 45 ofv theheat motor H is broken and the bimetallic strip 45 warps downwardly;therebymoving the valve-operating arm and its stud 55 downwardly to.cause the heads 56` of the studto press down on the push pin 26 andswing the lever 22 to low pilot nre position. The arm 50 may continue tomove downwardly after the lever22f`is inY low fire positionpdue to theprovision of the spring 60, which affords a yieldable or lostmotionconnection between the vvalve-operating arm 5D and its stud 55.The provision of this yieldable conrarirl'of the lever, designated atII'LVtermnates in a rounded end H8 which underlies the outer end portionof the bimetallic leaf 45. `The other arm I 9 ofthe bell crank leverextends up thrugh y the housing and hasan oiset upper end improf jectingthrough a keeper slot |2| provided inthe coverfof the control casing'.The keeper slot has# one margin formed with an integral lug |22 pro-y-`vid-ing latching shoulders |23 ands|24 cooperable,A with the offset endl20 of the bell crank ||5 to releasably securethe latching lever in idleor operative position.` Figure 12 shows the keeper ||5 in full lines inidle position, in which eventthermostatic control lis had. By shiftingthe leverv f over to the dotted line position shown in Figures 12 and13, and engaging itwith the keeper shoulder |24,fthe bimetallic leaf 45isiiexed upwardly and retained in upwardly exed position out of therange of movement of the pin 26, thereby converting the mechanism into amanually controlled device.` When this is done the switchactuatingelements 82 and 83 lmay be removed or else adjusted so as not toexercise any control of the snap switch, land it, of course, may bepositioned as desired. yThe bell crank lever H5 is constituted ofresilient metal and its arm ||9 is so formed and assembled that underthe inuence of its own inherent resiliency it is biased to lhavelatching engagement with the margin of the keeper sloton which theshoulders |23 and |24 are formed. f A L While we have shown anddescribed several constructions in which the invention may beadvantageously embodied, it is to be understood that the constructionsshown have been selected merely for the purpose of illustration orexample, and that various changes in the size, shape, and arrangement..of `the, parts may be madepwithout departing from the spirit of theinvention or scope of the subjoined claims. A,

We claim: 1. A control mechanism of the character described for use inregulating the supply of oil and air to-an oil burner a'nd comprising aburner, a meteringk valve for regulating flow to the burner,

l, a .heat motor controlled in its action by means er including-.anelectric motor-driven fan, `a

nection in the motion transmission train between Y the heat motor H andthe valve makes it practical and convenient to set the switch-actuatingelement B3 so that it will not engage the switch operator 80 for apredetermined time after the metering valve has been shifted to lowpilot re position. Consequently, the fan motor continues to supplyforced draft to the burner after the metering valve has been shiftedto-low pilot re positiony thereby scavenging the burner and insurngcomplete and odorless combustion.

lThe present invention also proposes to provide control mechanism ofthis character with means for throwing the heat motor H out of action sothat, if desired, the control exercised over the switch controlling thestartingA and stopping of said fan motor, and two, independentlyadjustable, switch actuators carried by and movablev with said movablemotor element, one of said actuatorsfunctioning to close the switch onmovement of said motor element a predetermined distancein one direction,the other of said actuators functioning to open said switch uponpredeterminedmovement of said vmotor'element in an opposite direction.

v2; A control mechanism ofl the character described for use invregulating the subplyof oil and air to an oil burner and comprisingaburner, a casing having a liquid supply chamber provided with anoutlet, a metering valve for regulating flow through the outlet, abiinetalllc leaf operatively interrelated with the valve to control theposition thereof, an electric heating element combined with saidbimetallic leaf, a thermostat regulating the supply of currenty to saidelectric heating element, means for supplying air'to the burnerincluding an electric motor-driven fan, a switch controlling thestarting and stoppingfof said fan motor, and two adjustable actuatingelements for the the switch carried by and movable with'the bimetallicleaf, one of said elements functioning to close the switch on movement`of the leaf a predetermined distance in one direction, the other of saidelements functioning to open said switch upon predetermined movement ofthe leaf in an opposite direction'.

3. A control mechanism of the character described for use in regulatingthe supply of oil and air to an oilburner and comprising a burner, a.metering valve for regulating-dow to the burner. a heat motor controlledin its action by means responsive to the temperature to be regulated, avalve operator actuated by the heat motor, motion transmissionmeans'between said operator and said valve and including a yieldableconnection providing for continuedl movement of said heat motor afterthe valve is arrested in its low re position, means for supplying air tothe burner including an electric motor-driven fan, a switch controllingthe starting and stopping of the fan motor, and means utilizing saidcontinued movement of the heat motor for opening said switch andstopping the motor a predetermined time after the valve is moved to lowre position.

4. A control mechanism of the character described for use in regulatingthe supply oi oil and air to an oil burner and comprising a burner, acasing having a liquid supply chamber provided with an outlet,armetering valve forl regulating flow through said outlet, levermechanism mounted in the casing and cooperable with the valve forshifting the same from high fire to low fire pilot position, high andlow fire stops for the valve, a cover for the casing having an openingtherein overlying said lever mechanism, a vmotor transmission pinslidable through said opening and operatively engaged with the levermechanism in the casing, said pin projecting beyond the casing, acontrol housing mounted onand secured to the cover of the casing at oneside of Asaid pin, a terminal board of insulating materialsupportedwithin the housing in spaced relation with theV Walls thereof, abimetallic leaf supported on said terminal board, a valve-operating armsecured to the free end of said leaf and projecting upwardly therefrominto an overlying relation with the pin, a spring projected motiontransmission element carried by the portion of the arm overlying' thepin and engageable with the pin, an electric heating element combinedwith the leaf, a thermostat for regulating the supply of current to saidelectric heating element, means supplying air to the4 burner including amotor-driven fan, a snap action switch controlling starting and stoppingof said fan motor, means actuated by said leaf for opening said switchand stopping the motor a predetermined time after the valve is moved tolow fire position.

5. A control mechanism of the character described for use in regulatingthe supply of oil and air to an oil burner comprising a burner, a casinghaving a liquid supply chamber provided with an outlet, a metering`valve for regulating flow through said outlet, high and low fire stopsfor the valve, a bimetallic leaf, motion transmission means between saidleaf and said valve including a yieldable connection providing forcontinued movement of the leaf after the valveis arrested in low fireposition, an electric heating element combined with said leaf, athermostat for regulating the supply of current to Vsaid element, meansfor supplying air to the burner including a motor-driven fan, a snapaction switch con;

scribed for use in regulating the supply of oil and* air to an oilburner and comprising a burner, a casing having a liquid supply chamberprovided with an outlet, a metering valve for regulating iiow throughsaid outlet, high and low re stops for the valve, a bimetallic leafcooperable with the valve to control the position thereof from a highfire position to a low re position, an electric heating element combinedwith said leaf, a thermostat for regulating the supply of current tosaid electric heating element, means for supplying air to the burnerincluding a motor-driven fan, a snap-acting switch controlling thestarting and stopping of said fan motor, a switch operator combined withthe switch and projecting therefrom, a bracket carried'by said leaf, andan actuating element for the switch operator adjustably supported on thebracket and cooperable with the operator to open the switch and stop themotor a predetermined time after the valve is moved to low re position.

7. A control mechanism of the character described for use in regulatingthe supply of oil and air to an oil burner and comprising a burner, acasing having a liquid supply chamber provided with an outlet, ametering valve for regulating flow through said outlet, high and low nrestops ,for the valve, a bimetallic leaf cooperable with the valve tocontrol the position thereof from a high re positionto a low fireposition, an electric heating element combined with said leaf, athermostat for regulating the supply of current to said electric heatingelement, means for supplying air to the burner including a motor-drivenfan, a snap-acting switch controlling the starting and stopping of saidfan motor, a switch operator combined with the switch and projectingtherefrom, a bracket carried by said leaf, and two independentlyadjustable actuators for the switch carried by said bracket, one of saidactuators functioning to close the switch on movement of said bracket apredetermined distance in one direction, the other of said actuatorsopening the switch upon predetermined movement of the bracketin anopposite direction.

8. A control mechanism for use in regulating the supply of oil and airto an oil burner and comprising a burner, a metering valve forregulating flow of oil to the burner, a heat motor having a bimetallicleaf interconnected with the valve for controlling the position thereof,means for supplying air to the burner including an electric motor-drivenfan. a switch controlling the starting and stopping of said electric fanmotor, an operator for said switch adjacent said leaf, a bracket carriedby the leaf and overlying said operator, and two switch actuatorsadjustably supported on said bracket, one of said actuators engaging theoperator from above and the other engaging the same from below wherebyone of said actuators functions to close the switch upon predeterminedmovement of the leaf in one direction and the other functions to openthe switch upon predetermined movement of the leaf in the oppositedirection.

9. A control mechanism for use in regulating the supply of oil and airto an oil burner and comprising a burner, a metering valve for regu- 10.A control mechanism for use in regulatingl the` supply of oil andairtoan oil burner and comprising a burner, a metering valve for regulatingflow of oil to the burner, a heat motor havi ing a'bimetallic leafinterconnected with the valve for controlling the position thereof,means for supplying air tothe burner including-an electric motor-drivenfan, a switch controlling the starting and stopping of said electric fanmotor, an operator'for said switch adjacent said leaf, a bracket carriedby the leaf and ,overlying said operaton'and two switch actuating screwsthreadedly interconnected with said bracket, one of said screws having acollar engageable with said operator from above, the other having acollar engageable with said operator from below. d

11. A control mechanism for use in regulating the supply of oil and air`to an oil burner and comprising a burner, a metering valve forregulating fiow of oil to the burner, high and low fire stops for thevalve, a heat motor having a bimetallic leaf, motion transmission meansbetween said lleaf and said valve including a yieldable connectionproviding for continued movement of said leaf after the valve isarrested in low ire position, meansfo'r-'supplying air to the burnerincluding an electric motor-driveny fan, a switch controlling thestarting and stopping of said electric fan motor, and a switch actuatoradjustably supported on the leaf actuator and utilizing the continuedmovement ofthe leaf after the valve is arrested in low fire position tovautomatically open the switch and stop the motor after the lapse of apredetermined interval of time.

12. A control mechanism for use in regulating the supply of oil and airto an oil burner and comprising a burner,y a metering valve forregulating iiow of oil to the burner, high and low fire stops for thevalve, a heat motor having a bimetallic leaf, motion transmission meansbetween said leafand said valvev including a yieldable connectionproviding for continued movement of said leaf after the valve isarrested in low iire position, means for supplying air to the burnerincluding an electric motor-driven fan, a switch controlling thestarting and stopping of said electric fan motor, an operator for theswitch adjacent said leaf, and two switch actuators adjustably supportedon said bracket, oneof said actuators engaging the operator from aboveand utilizing the continued movement of the leaf after the pilot valveisarrested in its low fire position to automatically open theeswitch andVstop the motor after the lapse of the predetermined Ainterval of time,the other of said actuators engaging the operator from below andfunctioning to automatically close the switch and start vthe motor afterthe valve opens to a predetermined 2,343,188 1 nung new of on to thebumeea heat motor havf stops for the valve, a heat motorfhavlng a bi-`metallicleaf interconnected with the valve to control the` positionthereof, means for'supplying air to the burner including an electricmotor-v 6 driven fan, a double throwsnap action switchV controlling thestarting andstopping of said electric fan motor, an operator for saidswitch adjacent saidv leaf, and means carried by the leaf and cooperablewith said operator to effect clos- 10 ing of the switch uponpredetermined movement of the leaf in one direction and opening of theswitch upon predetermined movement of the leaf in an opposite direction.

14. A control mechanism for use in regulating the supply of .oil and airto an oil burner and supply chamber `provided with an outlet, a meteringvalve for regulating flow through said outlet, lever mechanism mountedin the casing and '20 cooperable with the valve for shifting "the samefrom high re to low fire position, high and low fire stops for thevalve,'a cover for the casing having an opening therein overlying saidlever mechanism, a motion transmission pin slidable beyond said openingand operatively engagedA with the lever mechanism in the casing, saidpin projecting beyond the casing, a control housing mounted on andsecured to the cover of the cas-- ing at one side of said pin, aterminal board of insulating material supported within the housing inspaced relation with the walls thereof, a heat motor includinga.bi-metallic leaf supported on the terminal board, a valve-operating armsecured to the free end of -said leaf and projecting outwardly of thehousing and .finto the overlying relation with the pin, a springprojected motion transmission element carried by the portion of the 'armoverlying the pin and engageable with the pin, means supplying'air 40tothe burner including anelectric motor-driven fan, a doubleV throw snapacting switch controlling starting and stopping of said fanmotor, anoperator for the switch adjacent the leaf, a bracket carried by theleafand overlying the operator, l and two Aswitch actuatingk screwsthreadedly interconnected with said bracket, one of said screws having acollar engageable with said operator from above, the other having acollar engageable withsaid operator from below.

15. A control mechanism for use in regulating the Asupply of oil and airto an oil burner, and comprising a burner, a main casingy having aliquid supply chamber provided with an Voutlet, a metering valve forregulating flow through said outlet, high and low fire stops for thevalve, acontrol housing mounted on the main casing, a terminal board ofinsulating material supported within said housing infspaced relation tothe walls thereof, a heat'motor lncludinga bimetallic leaf supported .onsaid terminal board, motion transmission means between the free end ofthe leaf .and said valve, means for supplying air to the burnerincluding an electric motor-driven fan, a double throw` snap actionswitch mounted on the terminal board adjacent said bimetallic leaf andconnected in circuit to sa-idfan motor to control the starting andstopping thereof, an operator for said switch adiacent the leaf, andmeans carried by and movable with the leaf and cooperable with theoperator to effect opening and closing of the switch at predeterminedtimes.

comprising a burner, a casing having a liquid 16. A control mechanismfor use in regulating the supply of oil and air to an oil burner,

and comprising a burner, a main casing having a liquid supply chamberprovided with an outlet, a metering valve for regulating flow throughsaid outlet, high and low fire stops for the valve, a control housingmounted on the main, casing, a terminal board of insulating materialsupported within said housing in. spaced relation to the` walls thereof,a heat motor including a. blmetallic leaf Supported on said terminalboard, motion transmission means between the free end of the leaf andsaid valve, means for supplying air to the burner including an electricmotor-driven fan, a double throw snap action switch mounted on theterminal board advjacent said bimetallic leaf and connected in cirplychamber provided with an outlet, a metering valve for regulating flowthrough said outlet, manually adjustable cam means for controlling theposition of the valve from 'fully closed position through intermediatenre position 4to high fire position, lever mechanism also interconnectedwith the valve for controlling the posi` tion thereof within the rangepermitted by the 5 manually adjustable cam means, high and low tirestops cooperable with said lever mechanism, a control housing mounted onthe main casing, a heat motor controlled in its action by meansresponsive to the temperature to be regulated and l0 including abimetallic leaf supported in the control housing, motion transmissionmeans freely coupled to the leaf but actuated thereby to control the'position of the valve, a latching lever fulcrumed within the controlhousing and having an arm engageable with the bimetallic leaf, and

an arm projecting exteriorly of the control housing, the control housinghaving a slot through which the projecting end of said last named armextends, said slot having latching shoulders cooperable with theadjacent portion of the projecting arm of the lever to releasably securethelever in'idle position with its rst named arm out of engagement withthe bimetallic leaf or in latching position with its ilrst named armengaged with and warping the leaf out of operative nterengagement withsaid motion transmission means whereby the control mechanism is subjectsolely to the control of said manually adjustable cam means.

ROY W. JOHNSON. WIILIAM A. BIERMANN.

